Necrotizing Fasciitis

Topic updated on 02/23/15 11:12am
  • Necrotizing fasciitis is a life threatening infection that spreads along soft tissue planes
  • Risk factors
    • immune suppression
      • diabetes
      • AIDS
      • cancer
    • bacterial introduction
      • IV drug use
      • hypodermic therapeutic injections
      • insect bites
      • skin abrasions
      • abdominal and perineal surgery
    • other host factors
      • obesity
  • Associated conditions
    • cellulitis
      • overlying cellulitis may or may not be present
  • Prognosis
    • life threatening infection
      • mortality rate of 32%
      • mortality correlates with time to surgical intervention
 Necrotizing Fasciitis Classification
Type Organism Characteristics
Type 1 q Polymicrobial
Typical 4-5 aerobic and anaerobic species cultured:
• non-Group A Strep
• anaerobes including Clostridia
• facultative anaerobes
• enterobacteria
• Synergistic virulence between organisms
 • Most common (80-90%)
 • Seen in immunosuppressed (diabetics and cancer patients)
 • Postop abdominal and perineal infections
Type 2  Monomicrobial
• Group A β-hemolytic Streptococci is most common organism isolated
 • 5% of cases
 • Seen in healthy patients
 • Extremities
Type 3 Marine Vibrio vulnificus
(gram negative rods)
 • Marine exposure
Type 4 MRSA  
  • Symptoms
    • early
      • localized abscess or cellulitis with rapid progression
      • minimal swelling
      • no trauma or discoloration
    • late findings
      • severe pain
      • high fever, chills and rigors
      • tachycardia
  • Physical exam
    • skin bullae
    • discoloration 
      • ischemic patches
      • cutaneous gangrene
    • swelling, edema
    • dermal induration and erythema
    • subcutaneous emphysema (gas producing organisms)
  • Radiographs
    • not required for diagnosis or treatment
  • Gas gangrene 
  • Biopsy 
    • indications
      • emergent frozen section can confirm diagnosis in early cases 
    • technique
      • take 1x1x1cm tissue sample
      • can be performed at bedside or in operating room
      • surgical intervention should not be delayed to obtain
    • histological findings
      • necrosis of fascial layer
      • microorganisms within fascial layer
      • PMN infiltration
      • fibrinous thrombi in arteries and veins and necrosis of arterial and venous walls
  • LRINEC Scoring system
    • score > 6 has PPV of 92% of having necrotizing fasciitis
      • CRP (mg/L) 
        • ≥150: 4 points
      • WBC count (×103/mm3)
        • <15: 0 points
        • 15–25: 1 point
        • >25: 2 points
      • Hemoglobin (g/dL)
        • >13.5: 0 points
        • 11–13.5: 1 point
        • <11: 2 points
      • Sodium (mmol/L)
        • <135: 2 points
      • Creatinine (umol/L)
        • >141: 2 points
      • Glucose (mmol/L)
        • >10: 1 point
  • Operative
    • emergency radical debridement with broad-spectrum IV antibiotics post q
      • indications
        • whenever suspicion for necrotizing fasciitis
      • operative findings
        • liquefied subcutaneous fat
        • dishwater pus
        • muscle necrosis
        • venous thrombosis
      • technique
        • hemodynamic monitoring with systemic resuscitation is critical
        • hyperbaric oxygen chamber if anaerobic organism identified
      • antibiotics
        • initial antibiotics
          • start empirically with penicillin, clindamycin, metronidazole, and an aminoglycoside
        • definitive antibiotics
          • penicillin G
            • for strep or clostridium
          • imipenem or doripenem or meropenem
            • for polymicrobial
          • add vancomycin or daptomycin
            • if MRSA suspected
    • amputation
      • indications
        • low threshold for amputation when life threatening


Please Rate Educational Value!
Average 4.0 of 33 Ratings

Qbank (4 Questions)

(OBQ12.136) A 16-year-old male presents to the emergency department one day after scratching his leg on a piece of scrap metal. He reports a progressive rash on his leg that has advanced over the last several hours. In the emergency room his temperature is 102.8 degrees and his systolic blood pressure is 98 mmHg. On physical exam the clinical finding shown in Figure A is found. What would be the most appropriate next step in treatment. Topic Review Topic
FIGURES: A          

1. MRI
2. Biopsy with urgent frozen section in the operating room
3. Needle aspiration
4. CT
5. Ultrasound

(OBQ10.89) Poor outcomes with necrotizing fasciitis have been associated with which of the following factors? Topic Review Topic

1. Pre-existing cardiac dysfunction
2. Polymicrobial infection
3. Use of hyperbaric oxygen
4. Intravenous drug abuse
5. Delay in time to diagnosis

(OBQ04.217) A 52-year-old diabetic male sustained minor blunt trauma to his left thigh 10 hours prior to presentation. He initially complained of extreme thigh pain with erythema and swelling but rapidly developed bullae and worsening erythema over the affected area along with fever and tachycardia. A clinical photo is shown in Figure A. What clinical factor has been shown to reduce mortality when treating this pathology? Topic Review Topic
FIGURES: A          

1. Presence of MRI findings
2. Administration of pressors
3. Decreasing time from admission to surgery
4. Immediate identification of causative organism
5. Location of injury

(OBQ04.264) A 56-year-old diabetic male presents to the emergency department by ambulance after developing high-grade fevers, malaise, and altered mental status. Upon presentation, he is found to be hypotensive and initial labs show an elevated WBC with a profound left shift. Figure A shows skin manifestations confined to the foot at initial presentation. He is started on broad spectrum antibiotics. Upon follow-up exam 3 hours later his clinical condition deteriorates (Figure B) and he is taken to the operating room for surgical debridement. In a bacterial culture, what would be the most common single isolate for this condition? Topic Review Topic
FIGURES: A   B        

1. Staphylococcus aureus
2. Staphylococcus epidermidis
3. Group A streptococcus
4. Enterobacteriaceae
5. Pseudomonas



Topic Comments